Venting or deodorizing the water closet is a subject that has been attacked by many pioneer inventors for many years. Among all the prior arts, three categories can be found. The first one is to solve the problem by adapting a newly designed bowl or remodeling the bathroom wall where an additional vent pipe is installed. The second one is to install venting devices inside the seat or the tank cover. The third one where this invention belongs to is to utilize the existing water closet structure and mechanism. The main apparatus of this deodorizing device is hidden inside the tank. The cost of production is the lowest, the use and installation are the easiest among these three categories. This is the only feasible one for every household. Although some inventions in this group seem to be heavy, applying excessive weight and torsion onto the overflow pipe; this invention is emphasized light weight of the embodiment, less than one half pound. The center of weight and spinning force is balanced at the axis of the embodiment that shares the same axis of the overflow pipe. Utilizing active water closet deodorizer will result in a comfortable environment and great saving of water, which is a global wide precious natural resource of the next century. This invention has a blight future.